The art of building a smooth cosmic distance ladder in a perturbed universe. Issue 8 (1st August 2022)

• Record Type: Journal Article
• Authors: Umeh, Obinna
• Is Part Of: Journal of cosmology and astroparticle physics. Volume 2022:Issue 8(2022)
• Publication Date: 2022-08-01
• Subjects: Cosmological perturbation theory in GR and beyond -- cosmological parameters from LSS; Cosmology -- Periodicals; Astrophysics -- Periodicals; 523.0105
• DOI: 10.1088/1475-7516/2022/08/023
• Languages: English
• ISSNs: 1475-7516

Abstract

Abstract: How does a smooth cosmic distance ladder emerge from observations made from a single location in a lumpy Universe? Distances to the Type Ia supernova (SN1A) in the Hubble flow are anchored on local distance measurements to sources that are very nearby. We described how this configuration could be built in a perturbed universe where lumpiness is described as small perturbations on top of a flat Friedmann-Lemaıtre Robertson-Walker (FLRW) spacetime. We show that there is a non-negligible modification (about 11%) to the background FLRW area distance due to the presence of inhomogeneities in the immediate neighbourhood of an observer. We find that the modification is sourced by the electric part of the Weyl tensor indicating a tidal deformation of the local spacetime of the observer. We show in detail how it could impact the calibration of the SN1A absolute magnitude in the Hubble flow. We show that it could potentially resolve the SN1A absolute magnitude and Hubble tensions simultaneously without the need for early or late dark energy.